Capitalists and capitalist states are always motivated by economic considerations.

Marx thought that he had found a "scientific" basis
for socialism by seeing all important social activity as shaped
by the means of production and means of exchange in the culture
under study. He had many brilliant insights, and his method of
analysis can still be useful today; but it seems clear that capitalist
nations and their populations are often swept up in nationalistic,
religious, or other manias which override their economic self-interest.
The Underground Man observes in Notes from Underground
that people often act against their own best interests--and that
seems to be as true of nations as it is of individuals.

During the Vietnam War radicals often quoted a statement of President
Eisenhower's that Southeast Asia should not be "lost"
to Communism because of its valuable natural resources. But anyone
studying the Vietnam war would be hard-pressed to find evidence
of any economic benefit accruing to the U.S. from it. Indeed,
Eisenhower probably felt compelled to justify what was essentially
an ideological battle in capitalist terms because such attitudes
are considered "rational" in capitalist nations.

A more sophisticated Marxist analysis argues that the domination
of world economies and the creation of neocolonialist hegemony
(control) requires the defeat of Communism, so that even very
costly wars have a long-range rationale of making the world safe
for corporate profit. This is an argument that can be wielded
with great power, but it is not a universal explanation for foreign
policy within capitalist nations. It should be noted that socialist
states have hardly been immune from allowing economic considerations
to influence their foreign policy either.